Browsing by Author "Vikram Sharma"

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Assessment of Existing Himalayan Glacier Inventories for Glacier Studies: A Case Study from the Ravi Basin of North-Western Himalaya (India)
(Springer International Publishing, 2023) Ishtiaq Ahmed; Vikram Sharma; Rinku Kumar; Devi Lal; Rajan Bhandari; Pritam Chand
Outside of the polar regions, the Hindukush-Karakoram-Himalaya (HKH) has the highest cluster of snow cover and glaciers, which offer various ecosystem services, including water, to the billions of people who live across this region. A glacier inventory is a vital prerequisite for researching a wide range of diverse phenomena, processes, and effects of such glacier changes across these regions. In recent years, several glacier inventories are available for the HKH region, namely, the Geological Survey of India (GSI) Glacier Inventory, the Space Application Center (SAC) Glacier Inventory, the International Centre for Integrated Mountain Development (ICIMOD) Glacier Inventory, Randolph Glacier Inventory (RGI), and Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM) Glacier Inventory (GGI). Prior to being used for any glacier investigations, it’s critical to evaluate the quality and consistency of these inventory datasets. Thus, the current study provides a detailed quality assessment of all these available glacier inventories by comparing them with the detailed Ravi basin glacier inventory (RBGI). The comprehensive RBGI was created using the Landsat Enhanced Thematic Mapper (ETM+) images (2002) with a supplement of medium- to high-resolution imagery and field validations. The RBGI consists of 285 glaciers in 2002 with a mapped area of 164.5 ± 7.5 km2. There are 71 glaciers out of the total glaciers that have debris-covered parts, which occupy 36.1 ± 2.1 km2 (~22% of the whole area covered by glaciers). Large variations were found in the glacial area (ranging from 202 to 112.7 km2) and a total number of glaciers (ranging from 299 to 192) mapped within the Ravi basin among these available glacier inventories. With few spatial differences in the total number of the glacier, their extent, and median elevation, it was found that the recently updated GGI inventory, which is incorporated into the revised version of RGI V6 for the Himalayan region, is most comparable to our RBGI inventory. Likely causes of the significant difference among these inventories include standard glacier definition (minimum area of glacier mapping and headwall definition), misinterpretation of the seasonal snow cover, demarcation of debris-covered areas, and consequences of excluding glacier sections in the shaded regions. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.
Climate-driven acceleration in forest evapotranspiration fuelling extreme rainfall events in the Himalaya
(IOP Publishing Ltd, 2021) Nilendu Singh; Jayendra Singh; Anil K. Gupta; Achim Brauning; A.P. Dimri; A.L. Ramanathan; Vikram Sharma; Reet Kamal Tiwari; Joyeeta Singh Chakraborty; Pankaj Chauhan; Tanuj Shukla; Mohit Singhal; Suman Rawat; Shefali Agarwal; P. Raja
Warming-induced expansion in vegetation coverage and activity can accelerate the montane hydrological regimes. However, the climate impacts on ecohydrology of forested valleys of the Himalaya are uncertain. In this study, utilizing results of about three centuries of cellulose isotope chronologies (δ 13C and δ 18O) of dominant tree species, geo-chronological proxies, bio-geophysical dataset and simulations including satellite observations, we show an activation in the ecophysiological processes including evapotranspiration (ET) since the 1950s. Observation suggests rapid greening, while isotopic records indicate enhanced assimilation and transpiration in deciduous species vis-a-vis conifers post 1950s. Given strong vegetation-precipitation feedback and superimposed on the increasing trends of conducive atmospheric factors affecting valley-scale convective processes, intensification in forest ET is manifesting in a progressive enhancement in extreme rainfall events (EREs) since the last few decades. Results suggest that representation of ecophysiological processes and dynamics of seasonal moisture loading in observational and modelling framework is critical for understanding EREs under climate change. © 2021 The Author(s). Published by IOP Publishing Ltd.
Deep learning models for large-scale slope instability examination in Western Uttarakhand, India
(Springer Science and Business Media Deutschland GmbH, 2022) Vishnu Himanshu Ratnam Pandey; Ashutosh Kainthola; Vikram Sharma; Abhishek Srivastav; T. Jayal; T.N. Singh
Slope failures are avoidable accidents in most of the scenarios. The eventuality of a failure leads to loss of lives and destruction, especially in hilly areas. Investigation, analysis and prediction of slope failure is a reliable approach to avert such mishaps. Hence, the present research work delves into the prediction of landslides and slope failures through numerical simulation and a deep learning approach. Field attributes and laboratory-tested strength data from Lower Tons Valley, Northern India has been taken as a case study. Initially, a total of 185 slope models were simulated in a finite difference code by varying four slope parameters, namely, slope angle, slope height, cohesion and angle of internal friction. These simulated results were further divided into two parts, one part with 148 datasets for the training of models and other part consisting of 37 datasets for testing of models. Two artificial neural network prediction models, along with a conventional multi-linear regression model was developed and their accuracy was accessed. The developed neural network models superseded the conventional model, in terms of performance and accuracy, as shown by statistical approaches R2 and mean squared error values. Moreover, the neural network model with Adam optimizer achieved higher statistical accuracy than the one with stochastic gradient descent optimizer. However, all these deep learning models demonstrate significant performance, and can be used by geo-engineers for swift prediction of safety factors for excavated slopes in the study area. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Evaluating instability & failure pattern of landslides, Giri valley, Northwest Himalaya, India
(Springer Science and Business Media Deutschland GmbH, 2024) Raghuveer Negi; Saraswati Prakash Sati; Vikram Sharma; Manojit Samanta; Vipin Kumar; Mohit Kumar Puniya; Sanjay Singh Rana; Debi Prasanna Kanungo
This study aimed to evaluate the slope instability and failure patterns of four major landslides of the Giri Valley, Northwest Himalaya. The study area i.e., Giri valley has not been studied much despite a history of frequent landslides in the region. In order to fulfill this gap and evaluate the potential failure pattern, methodology involved a comprehensive analysis of Rock Mass Rating (RMR), Kinematic Analysis (KA), Slope Mass Rating (SMR), Geotechnical characterization (GA), and Limit Equilibrium Method (LEM). Results revealed that the all four landslide slopes exhibit pronounced fracturing and low Rock Quality Designation (RQD) in the rock masses, which is attributed to their spatial proximity to the Main Boundary Thrust (MBT) Fault in the region. The RMR values ranged from 28 to 38 and the SMR values ranged from 20 to 30, implying that the rock itself might not be too weak, but there could be other factors contributing to instability. The Kinematic Analysis revealed planar failure conditions in all the four landslides, indicating the possibility of landslides occurrence along well-defined planes of weakness in the rock mass. Further, The LEM based Factor of Safety (FOS) values ranged from 0.9 to 1.4, which can be attributed to a critical state, where even a small increase in driving forces or decrease in resisting forces could trigger a landslide. The low FOS values indicate a potential for instability, and mitigation measures may be necessary to ensure slope stability in the region. These measures could include slope reinforcement, drainage improvement, or restricting activities that could increase the driving forces on the slopes. These methods can be regionally replicable if the rock mass characteristics are similar across the region. However, site-specific data collection and analysis are crucial for accurate assessment. © The Author(s) 2024.
Hill slope stability examination along Lower Tons valley, Garhwal Himalayas, India
(Taylor and Francis Ltd., 2021) Ashutosh Kainthola; Vikram Sharma; Vishnu Himanshu Ratnam Pandey; Tripti Jayal; Mukesh Singh; Abhishek Srivastav; Prakash K. Singh; Prashant K. Champati Ray; Trilok Nath Singh
The present research details the remote sensing, geotechnical and seismic aspects of hill slopes in Lower Tons river valley, Garhwal Himalaya, India. The region is a part of Lesser Himalaya and holds religious and strategic importance. The studied span has been a site of slope failures in the past. The remote sensing investigation was used to characterize the geomorphological and hydrological attributes of the area. This information was used to delineate vulnerable locations. Along the road stretch of about 80 km, 80 tests were conducted to ascertain the soil particle distribution and plasticity indices; and 33 tests for shear strength properties. Using the geotechnical parameters, numerical simulation was conducted for two slopes of angle, 40° and 50°, with a consistent height of 50 m. Most of the slopes were stable at an angle of 40°, however, 30.30% (FEM) and 24.24% (FDM) of the analysed slopes failed for the steeper slope. Eventually, the pseudo-static analysis was done. The inclusion of seismicity increased the incidences of slope failure by 33.33% and 39.39% for the slope with an inclination of 40° and 50°, respectively. Afterwards, the slopes were optimized for their critical angle as a function of the safety factor. © 2021 The World Bank.
New inventory and dynamics of glacial lakes in Alaknanda basin, Uttarakhand, India from 1990 to 2020: A multi-temporal landsat analysis
(Elsevier B.V., 2025) Rekha Sahu; Parvendra Kumar; Rajnandini Gupta; Santram Ahirwar; Vikram Sharma
Glacial lakes are critical components of high-altitude mountainous regions in the Himalayas. In recent years, glaciers have rapidly receded due to climate change, resulting in the formation of glacial lakes with substantial risks for downstream communities and infrastructure. The present study uses Landsat satellite data to create a comprehensive glacial lake inventory in the Alaknanda Basin, focusing on spatiotemporal changes between 1990 and 2020. The study has recorded 73 glacial lakes (≥0.003 km2) with a total surface area of 2.538 ± 0.037 km2 in 2020. The mean depth and volume of glacial lakes were assessed as 7.17 m and 0.432 x 106m3, respectively. During 1990–2020, the total glacial lake area has increased from 0.748 ± 0.020 km2 to 2.538 ± 0.037 km2 with a growth of ∼1.790 km2 (239%; 7.97% a−1). Additionally, 15 common glacial lakes have shown significant growth rates of 91.24% (3.04% a-1). Among all the glacial lakes, tiny lakes (<0.02 km2) have shown the maximum growth in both numbers (+33) and area (477.92%; 15.93% a−1). Moraine-dammed lakes have expanded more rapidly in terms of number (+27), while supraglacial lakes have exhibited a higher rate of areal (1771.71%; 59.06% a−1) expansion. Based on the current inventory, flood hazard studies in the Alaknanda Basin can be carried out for a better understanding of glacial-climate related dynamics. © 2025 Elsevier B.V.
Quest for disaster-resilient roads in the Himalaya
(Indian Academy of Sciences, 2021) Shubhra Sharma; S.P. Sati; Y.P. Sundriyal; Vikram Sharma; Harsh Dobhal
Mountain roads are important lifelines and the most critical means for connectivity in the Himalayan villages of India. However, the inherent geological, geomorphological, ecological and climate fragility of the terrain warrants critical scientific investigations for the roads to sustain the vagaries of nature. Further, the increased frequency of extreme events with the ongoing climate change increases the potential impact of disasters. This note highlights the major challenges and issues faced with the ongoing road-widening projects in the country. It cautions against the uniform standard of road widening and the need to increase sensitivity towards appreciating the terrain fragility. © 2021
Spatio-temporal variation of biomass burning fires over Indian region using satellite data
(Elsevier, 2022) Darga Saheb Shaik; Yogesh Kant; M. Sateesh; Vikram Sharma; Deependra Singh Rawat; H.C. Chandola
The present study analyses the satellite derived active fire occurrences over Indian region during 2003–2018 based on moderate resolution imaging spectroradiometer (MODIS) and visible infrared imaging radiometer suite (VIIRS) sensors. The biomass fires show a large spatial and temporal variation with maxima observed in two phases: (1) premonsoon (combination forest fires and crop residue burning) and (2) postmonsoon period (crop residue burning only). On an annual average, the fraction of fire occurrences during premonsoon and postmonsoon is observed to be 57% and 24% from MODIS and 61% and 19% from VIIRS, respectively. Significant interannual variability of fire count was observed over Indian region. The annual average of active fire counts was found to be ~75,786 for MODIS and ~574,381 for VIIRS, respectively and also show the significant (95% confidence) increasing trend with a rate of 2.7% yr–1 and 3.4% yr–1 for MODIS and VIIRS, respectively. Regionally, most of the states (8 states) show the significantly increasing trends (10–30% yr–1) except north-east states (6 states) were found the decreasing trends (2–5% yr–1). Further, there were seven biomass burning (BB) hotspot regions are identified over India based on the 16 years of MODIS statistical fire density map. Annual fraction of fire types (either forest fire or crop residue burning) derived using MODIS land cover type product and were found range from 40% to 57% of annual total fires from forest and 39% to 55% from crop residue respectively on an all-India basis and has a strong regional/seasonal variation. These results on BB hotspots will be useful to address the regional fire mitigation strategies and emissions sources in India. © 2023 Elsevier Ltd. All rights reserved.
Tree-Ring Isotopic Records Suggest Seasonal Importance of Moisture Dynamics Over Glacial Valleys of the Central Himalaya
(Frontiers Media S.A., 2022) Nilendu Singh; Mayank Shekhar; Bikash Ranjan Parida; Anil K. Gupta; Kalachand Sain; Santosh K. Rai; Achim Bräuning; Joyeeta Singh Charkaborty; Vikram Sharma; Reet Kamal Tiwari; Pankaj Chauhan; Leonardo Montagnani
Accelerated glacier mass loss is primarily attributed to greenhouse-induced global warming. Land–climate interactions have increasingly been recognized as an important forcing at the regional-local scale, but the related effects on the Himalayan glaciers are less explored and thought to be an important factor regulating spatial heterogeneity. The aim of the present study is a multi-decadal approximation of glacier—hydroclimate interaction over the western region of the central Himalaya (WCH). Multi-species, highly coherent, tree-ring cellulose δ18O chronologies from three sites across the WCH were used to derive atmospheric humidity (Atmospheric Moisture Content: AMC) record of the last four centuries. Annual-scale AMC reconstruction implies a decreasing regional atmospheric moisture since the mid-19th century and a sharp decline in recent decades (1960s). Coherency analyses between regional AMC and glacier mass balance (GMB) indicate an abrupt phase-shift in the relationship after the 1960s within a common record of the last 273 years. To ascertain the cause of this phase-shift, annual AMC was disintegrated into seasonal-scale, utilizing ∼200 years of δ18O record of a deciduous tree species. Seasonal (winter: October–March; summer: April–September) AMC reconstructions and disaggregation results indicate higher sensitivity of regional ice-mass variability to winter moisture dynamics than summer.Winter season AMC reconstruction confirms a revival of winter westerlies-driven moisture influx in the region since the 1970 s. Meanwhile, the record for the summer season AMC indicates a gradual decline in moisture influx from the beginning of the 20th century. Interestingly, despite a prominent decline in Indian summer monsoon (ISM) precipitation after the mid-20th century, the summer season AMC—GMB relation remained stable. We hypothesize that decadal-scale greening, and consequently increased evapotranspiration and pre-monsoon precipitation might have been recycled through the summer season, to compensate for the ISM part of precipitation. However, isotope-enabled ecophysiological models and measurements would strengthen this hypothesis. In addition, high-resolution radiative forcing and long-term vegetation greening trends point towards a probable influence of valley greening on GMB. Our results indicate that attribution of ice mass to large-scale dynamics is likely to be modulated by local vegetation changes. This study contributes to the understanding of long-term hydroclimate—ice mass variability in the central Himalaya, where predictions are crucial for managing water resources and ecosystems. Copyright © 2022 Singh, Shekhar, Parida, Gupta, Sain, Rai, Bräuning, Singh Charkaborty, Sharma, Kamal Tiwari, Chauhan and Montagnani.
Vulnerability Assessment of Landslide with the Help of Geospatial Approach in Western Himalayas, Upper Basin of River Sutlej, India
(Springer Science and Business Media Deutschland GmbH, 2022) Amit Jamwal; Vikram Sharma
Vulnerability assessment is an important part of environmental management, and this approach is used for the identification of hazards and its potential risk in the upper basin of the river Sutlej. The geospatial tool was used to analyse, monitor and map landslide vulnerability. Rockslide, rock fall, slump, earthflow, and subsidence types of landslides were identified in the field. High summital convexity (1), rectilinear (0.8), high relative relief (>1000 m), high dissection ratio (>0.97), less forest cover (8%), slope aspects; southeast (1), south (0.9), the fine texture of soil (1), subhumid region (1), limestone-based lithology (0.9), high earthquakes magnitudes (1), and hydropower construction (1) were the major factors that indicated a high degree of vulnerability (0.68) and a high weighted score (0.58). The major finding of the vulnerability assessment indicated that 27% (1812 km2) area of the basin had a high vulnerability of landslide; however, 39% (2617 km2) area of the basin exists with low vulnerability. In the future, if anthropogenic activities increase in this basin, then the impacts of landslides and their loss of physical environment shall be increased. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.